MagnitudeOS/lwip
1
0
Fork 0
forked from Imagelibrary/lwip
Code Pull Requests Activity

Improve system abstraction layer doxygen docs by moving documentation from sys_arch.txt to the corresponding functions

Browse Source
This commit is contained in:
Dirk Ziegelmeier
2017-10-17 22:30:51 +02:00
parent 33f29af0b6
commit 26b2628f01
2 changed files with 108 additions and 227 deletions
Download Patch File Download Diff File Expand all files Collapse all files

208
doc/sys_arch.txt
View File

@@ -38,214 +38,6 @@ allows both using pointers or actual OS structures to be used. This way, memory
required for such types can be either allocated in place (globally or on the
stack) or on the heap (allocated internally in the "*_new()" functions).
The following functions must be implemented by the sys_arch:
- void sys_init(void)
Is called to initialize the sys_arch layer.
- err_t sys_sem_new(sys_sem_t *sem, u8_t count)
Creates a new semaphore. The semaphore is allocated to the memory that 'sem'
points to (which can be both a pointer or the actual OS structure).
The "count" argument specifies the initial state of the semaphore (which is
either 0 or 1).
If the semaphore has been created, ERR_OK should be returned. Returning any
other error will provide a hint what went wrong, but except for assertions,
no real error handling is implemented.
- void sys_sem_free(sys_sem_t *sem)
Deallocates a semaphore.
- void sys_sem_signal(sys_sem_t *sem)
Signals a semaphore.
- u32_t sys_arch_sem_wait(sys_sem_t *sem, u32_t timeout)
Blocks the thread while waiting for the semaphore to be signaled. If the
"timeout" argument is non-zero, the thread should only be blocked for the
specified time (measured in milliseconds). If the "timeout" argument is zero,
the thread should be blocked until the semaphore is signalled.
The return value is SYS_ARCH_TIMEOUT if the semaphore wasn't signaled within
the specified time or any other value if it was signaled (with or without
waiting).
Notice that lwIP implements a function with a similar name,
sys_sem_wait(), that uses the sys_arch_sem_wait() function.
- int sys_sem_valid(sys_sem_t *sem)
Returns 1 if the semaphore is valid, 0 if it is not valid.
When using pointers, a simple way is to check the pointer for != NULL.
When directly using OS structures, implementing this may be more complex.
This may also be a define, in which case the function is not prototyped.
- void sys_sem_set_invalid(sys_sem_t *sem)
Invalidate a semaphore so that sys_sem_valid() returns 0.
ATTENTION: This does NOT mean that the semaphore shall be deallocated:
sys_sem_free() is always called before calling this function!
This may also be a define, in which case the function is not prototyped.
- void sys_mutex_new(sys_mutex_t *mutex)
Creates a new mutex. The mutex is allocated to the memory that 'mutex'
points to (which can be both a pointer or the actual OS structure).
If the mutex has been created, ERR_OK should be returned. Returning any
other error will provide a hint what went wrong, but except for assertions,
no real error handling is implemented.
- void sys_mutex_free(sys_mutex_t *mutex)
Deallocates a mutex.
- void sys_mutex_lock(sys_mutex_t *mutex)
Blocks the thread until the mutex can be grabbed.
- void sys_mutex_unlock(sys_mutex_t *mutex)
Releases the mutex previously locked through 'sys_mutex_lock()'.
- void sys_mutex_valid(sys_mutex_t *mutex)
Returns 1 if the mutes is valid, 0 if it is not valid.
When using pointers, a simple way is to check the pointer for != NULL.
When directly using OS structures, implementing this may be more complex.
This may also be a define, in which case the function is not prototyped.
- void sys_mutex_set_invalid(sys_mutex_t *mutex)
Invalidate a mutex so that sys_mutex_valid() returns 0.
ATTENTION: This does NOT mean that the mutex shall be deallocated:
sys_mutex_free() is always called before calling this function!
This may also be a define, in which case the function is not prototyped.
- err_t sys_mbox_new(sys_mbox_t *mbox, int size)
Creates an empty mailbox for maximum "size" elements. Elements stored
in mailboxes are pointers. You have to define macros "_MBOX_SIZE"
in your lwipopts.h, or ignore this parameter in your implementation
and use a default size.
If the mailbox has been created, ERR_OK should be returned. Returning any
other error will provide a hint what went wrong, but except for assertions,
no real error handling is implemented.
- void sys_mbox_free(sys_mbox_t *mbox)
Deallocates a mailbox. If there are messages still present in the
mailbox when the mailbox is deallocated, it is an indication of a
programming error in lwIP and the developer should be notified.
- void sys_mbox_post(sys_mbox_t *mbox, void *msg)
Posts the "msg" to the mailbox. This function have to block until
the "msg" is really posted.
- err_t sys_mbox_trypost(sys_mbox_t *mbox, void *msg)
Try to post the "msg" to the mailbox. Returns ERR_MEM if this one
is full, else, ERR_OK if the "msg" is posted.
- u32_t sys_arch_mbox_fetch(sys_mbox_t *mbox, void **msg, u32_t timeout)
Blocks the thread until a message arrives in the mailbox, but does
not block the thread longer than "timeout" milliseconds (similar to
the sys_arch_sem_wait() function). If "timeout" is 0, the thread should
be blocked until a message arrives. The "msg" argument is a result
parameter that is set by the function (i.e., by doing "*msg =
ptr"). The "msg" parameter maybe NULL to indicate that the message
should be dropped.
The return values are the same as for the sys_arch_sem_wait() function:
SYS_ARCH_TIMEOUT if there was a timeout, any other value if a messages
is received.
Note that a function with a similar name, sys_mbox_fetch(), is
implemented by lwIP.
- u32_t sys_arch_mbox_tryfetch(sys_mbox_t *mbox, void **msg)
This is similar to sys_arch_mbox_fetch, however if a message is not
present in the mailbox, it immediately returns with the code
SYS_MBOX_EMPTY. On success 0 is returned.
To allow for efficient implementations, this can be defined as a
function-like macro in sys_arch.h instead of a normal function. For
example, a naive implementation could be:
#define sys_arch_mbox_tryfetch(mbox,msg) \
sys_arch_mbox_fetch(mbox,msg,1)
although this would introduce unnecessary delays.
- int sys_mbox_valid(sys_mbox_t *mbox)
Returns 1 if the mailbox is valid, 0 if it is not valid.
When using pointers, a simple way is to check the pointer for != NULL.
When directly using OS structures, implementing this may be more complex.
This may also be a define, in which case the function is not prototyped.
- void sys_mbox_set_invalid(sys_mbox_t *mbox)
Invalidate a mailbox so that sys_mbox_valid() returns 0.
ATTENTION: This does NOT mean that the mailbox shall be deallocated:
sys_mbox_free() is always called before calling this function!
This may also be a define, in which case the function is not prototyped.
If threads are supported by the underlying operating system and if
such functionality is needed in lwIP, the following function will have
to be implemented as well:
- sys_thread_t sys_thread_new(char *name, void (* thread)(void *arg), void *arg, int stacksize, int prio)
Starts a new thread named "name" with priority "prio" that will begin its
execution in the function "thread()". The "arg" argument will be passed as an
argument to the thread() function. The stack size to used for this thread is
the "stacksize" parameter. The id of the new thread is returned. Both the id
and the priority are system dependent.
When lwIP is used from more than one context (e.g. from multiple threads OR from
main-loop and from interrupts), the SYS_LIGHTWEIGHT_PROT protection SHOULD be enabled!
- sys_prot_t sys_arch_protect(void)
This optional function does a "fast" critical region protection. This function
is only called during very short critical regions. An embedded system which
supports ISR-based drivers might want to implement this function by disabling
interrupts. Task-based systems might want to implement this by using a mutex
or disabling tasking. This function should support recursive calls from the
same task or interrupt. In other words, sys_arch_protect() could be called
while already protected.
The return value is opaque to lwip and passed to the sys_arch_unprotect() call
matching the sys_arch_protect() call at the same nesting level. This value
might be used to restore the status. However implementations may depend on
every call to sys_arch_protect() having a matching call to sys_arch_unprotect()
and thus can use a nesting count or a recursive mutex.
sys_arch_protect() is only required if your port is supporting an operating
system.
- void sys_arch_unprotect(sys_prot_t pval)
This optional function does a "fast" exit of critical region protection
nesting level. The value passed in pval is the opaque value returned the
respective call to sys_arch_protect(). See the documentation for
sys_arch_protect() for more information. This function is only required if
your port is supporting an operating system.
For some configurations, you also need:
- u32_t sys_now(void)
This optional function returns the current time in milliseconds (don't care
for wraparound, this is only used for time diffs).
Not implementing this function means you cannot use some modules (e.g. TCP
timestamps, internal timeouts for NO_SYS==1).
Note:
Be careful with using mem_malloc() in sys_arch. When malloc() refers to